The spreading of liquid nanodroplets of different initial radii R-0 is
studied using molecular dynamics simulation. Results for two distinct
systems, Pb on Cu(111), which is nonwetting, and a coarse-grained
polymer model, which wets the surface, are presented for Pb droplets
ranging in size from similar to 55 000 to 220 000 atoms and polymer
droplets ranging in size from similar to 200 000 to 780 000
monomers. In both cases, a precursor foot precedes the spreading of
the main droplet. This precursor foot spreads as r(f)(2)(t)=2D(eff)t
with an effective diffusion constant that exhibits a droplet-size
dependence D(eff)similar to R-0(1/2). The radius of the main droplet
r(b)(t)similar to R-0(4/5) is in agreement with kinetic models for the
cylindrical geometry studied.